Process for the preparation of sulfonylurea derivatives

Abstract: The present invention relates to a process for preparing the sulfonylchloride compound of formula (V) and the compound of formula (VIII), both of which are useful as an intermediate compound for preparing the sulfonylurea derivative of formula (I) and to a novel intermediate compound of formula (VIII): wherein R 1 represents hydrogen, C 1 -C 4 alkyl or phenyl, R 2 represents hydrogen, C 1 -C 4 alkyl, allyl or propargyl an R 3 represents hydrogen, methyl, ethyl or phenyl.

Description: BACKGROUND OF THE INVENTION 1. Field of Invention The present invention relates to a novel process for preparation of sulfonyl chloride derivatives. Particularly, the present invention relates to a novel process for preparation of sulfonyl chloride derivatives having the following general formula (V), wherein R 1 represents hydrogen, C 1 -C 4 alkyl or phenyl; R 2 represents hydrogen, C 1 -C 4 alkyl, allyl or propargyl; and R 3 represents hydrogen, methyl, ethyl or phenyl, characterized in that a pyrazole disulfide derivative of formula (XI), wherein R 1 , R 2 and R 3 are as defined above, is reacted with aqueous hydrochloric acid solution and hydrogen peroxide solution in the presence of an organic solvent. Therefore, it is the object of the present invention to provide a novel process for preparing an intermediate sulfonylchloride compound having the general formula (V) as defined above. The more pertinent and important features of the present invention have been outlined above in order that the detailed description of the invention which follows will be better understood and that the present contribution to the art can be fully appreciated. Those skilled in the art can appreciate that the conception and the specific embodiment disclosed herein may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Further, those skilled in the art can realize that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the claims. DISCLOSURE OF INVENTION Sulfonylchloride of formula (V) is a compound known as an intermediate compound useful for preparation of the sulfonylurea-based herbicide. European Early Published Patent No. 87,780 describes the method for preparing the intermediate compound of formula (V), in which a compound of formula (IX) is reacted with chlorine gas to prepare the pyrazole sulfonylchloride compound of formula (V), as depicted in the following reaction scheme: wherein R 1 , R 2 and R 3 are as defined above, and R 4 represents hydrogen or benzyl. However, since such known method uses chlorine gas which is highly poisonous to humans, the reaction should be practiced by means of a special safety apparatus. Further, this method has a disadvantage in that the by-product such as the compound of the following general formula (X): wherein R 1 , R 2 and R 3 are as defined above and X represents hydrogen or Cl, may be produced in a substantial amount due to the excessive strong reactivity of chlorine gas. The present invention establishes a method in which aqueous hydrochloric acid solution and hydrogen peroxide solution which are easy to handle and can be readily controlled in their reactivities are used in place of chlorine gas, and therefore the problems involved in the known method above can be solved. Specifically, according to the present invention the pyrazole sulfonylchloride derivative of formula (V) can be simply prepared by reacting a pyrazole disulfide derivative of formula (XI) with aqueous hydrochloric acid solution and hydrogen peroxide solution as depicted in the following reaction scheme: wherein R 1 , R 2 and R 3 are as defined above. The process for preparing the compound of formula (V) as defined above is a novel method which was never described in prior art up to the present and therefore is the object of the present invention. According to the process for preparing the compound of formula (V) of the present invention, the reaction can be carried out by reacting together the starting compound and the reactant each of which is dissolved in a separate solvent. When the reaction is carried out using the solvent, the solvent which is used is an organic solvent, for example, optionally halogenated alkane solvents such as n-hexane, dichloromethane, etc, toluene and the like. In this reaction, aqueous hydrochloric acid solution and hydrogen peroxide solution can be used in the ratio of 2.0 equivalent weights or more with respect to the starting disulfide compound of formula (XI) without any special limitation. However, in view of the fact that the production of by-products should be minimized, the reaction time should be shortened and the reaction efficiency should be increased, it is preferable that they are used in the ratio of 6.0 to 8.0 equivalent weights, respectively, with respect to the disulfide compound (XI). In addition, the reaction time of this reaction according to the present invention is prolonged in the case of the inner temperature of the reaction vessel below 20°C whereas the yield of the desired compound of formula (V) may be decreased at the temperature above 50°C due to hydrolysis of the compound of formula (V). Accordingly, the reactants should be carefully introduced so that the inner temperature of the reaction vessel can be maintained in the range of 30 to 50°C, more preferably 35 to 45°C. The disulfide compound of formula (XI) which can be used as the starting compound in the process for preparing the compound of formula (V) according to the present invention is a known compound and can be prepared, for example, by reacting a dithiocarbazate derivative of formula (XII) with a base and then oxidizing the reaction product in a conventional manner according to the method described in Korean Patent Application No. 92-24734 which belongs to the present inventors, as depicted in the following reaction scheme: - wherein R 1 , R 2 and R 3 are as defined above, and R represents C 1 -C 4 alkyl, C 2 -C 4 alkenyl, aralkyl(preferably benzyl) or aryl(preferably phenyl). The sulfonylchloride compound of formula (V): can be prepared according to the following method as explained in the method for preparation of sulfonylchloride compound of formula (V) wherein R 1 , R 2 and R 3 are as defined above. The present invention will be more specifically illustrated by the following examples. However, it should be understood that the present invention is not limited by these examples in any manner. Example 1: Preparation of bis(4-ethoxycarbonyl-1-methylpyrazole)-5-disulfide 2.12g(10.0 mmole) of benzyl 2-methyldithiocarbazate and 2.25g (10.2 mmole) were mixed with 2.40g of anhydrous ethanol and the mixture was heated to dissolve all the substances. To this heated mixture was added 3.89g of 21% sodium ethoxide and the mixture was refluxed for 8 hours and then distilled in vacuo to remove the solvent. The residue was dissolved in 2.50g of dichloromethane and 3.00g of water. The aqueous layer was adjusted to pH 7 with 20% sulfuric acid and 0.48g of 35% aqueous hydrogen peroxide solution was added thereto over one hour at room temperature. The reaction mixture was continuously stirred for further one hour at room temperature and allowed to separate the layers. The separated organic layer was dried over anhydrous magnesium sulfate and distilled in vacuo to remove the solvent to obtain 1.70g of the title compound (Yield 92%, Purity 98%). Example 2: Preparation of 4-ethoxycarbonyl-1-methylpyrazole-5-sulfonylchloride 1.67g(4.5 mmole) of the disulfide compound prepared in Example 1 was added to 3.75g(36.0 mmole) of 35% aqueous hydrochloric acid solution and 2.00g of dichloromethane at room temperature and the reaction mixture was warmed to 40°C and then maintained for 30 minutes at the same temperature. To this mixture was added 2.62g(27.0 mmole) of 35% aqueous hydrogen peroxide solution at 40 to 45°C over one hour and the whole mixture was continuously stirred for further one hour and then allowed to separate the layers. The separated organic layer was dried over anhydrous magnesium sulfate and the solvent was removed therefrom to obtain 2.16g of the title compound (Yield 95%, Purity 95%). Example 3: Preparation of 4-ethoxycarbonyl-1-methyl-5-pyrazole disulfide 30.6g of methyl 3-[2',2'-(diethoxycarbonyl)ethylidene]-2-methyldithiocarbazate and 8g of sodium ethoxide were added to 250ml of absolute ethanol and the mixture was heated under reflux in the nitrogen atmosphere for about 10 hours. When the reaction was completed, ethanol was distilled off and 200ml of water and 500ml of methylene dichloride were added to the residue. The mixture was adjusted to approximately pH 8 with 98% sulfuric acid to separate the layers. The aqueous layer was collected and then adjusted to pH 2. The resulting product was extracted with 500ml of methylene dichloride. 5.0g of 38% hydrogen peroxide was added to the methylene dichloride layer and the mixture was stirred for 3 hours at room temperature to complete the reaction. The reaction mixture was allowed to separate the layers and the organic layer was collected, dried over anhydrous magnesium sulfate and then distilled in vacuo to remove the solvent to obtain 16.8g of the title compound as brown solid (Yield 91%, Purity 98%). Example 4: Preparation of 4-ethoxycarbonyl-1-methylpyrazole-5-sulfonylchloride 370g of 4-ethoxycarbonyl-1-methyl-5-pyrazole disulfide, 390g of dichloromethane and 834g of 35% aqueous hydrochloric acid solution were introduced into a reaction flask. The reaction mixture was stirred at room temperature to dissolve the starting material and then 560g of 36% hydrogen peroxide was slowly added dropwise thereto over 2 hours during which the inner temperature of the flask should be maintained at approximately 40°C. After the addition of hydrogen peroxide was completed, the reaction mixture was stirred for further 30 minutes while maintaining the same temperature to complete the reaction, cooled to room temperature and then allowed to separate the layers. The separated organic layer was dried over anhydrous magnesium sulfate and the solvent was then removed therefrom to obtain 476g (Yield 94%) of the title compound as yellow liquid substance (Purity 94% as measured by gas chromatoaraphy). The more pertinent important features of the present invention have been outlined above in order that the detailed description of the invention will be better understood and that the present contribution to the art can be fully appreciated. Those skilled in the art can appreciate that the conception and the specific embodiment disclosed herein may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Further, those skilled in the art can realize that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the claims.

Claims: A process for preparing sulfonylchloride derivatives having the following general formula (V), wherein R 1 represents hydrogen, C 1 -C 4 alkyl or phenyl; R 2 represents hydrogen, C 1 -C 4 alkyl, allyl or propargyl; and R 3 represents hydrogen, methyl, ethyl or phenyl, characterized in that a pyrazole disulfide derivative of formula (XI), wherein R 1 , R 2 and R 3 are as defined above, is reacted with aqueous hydrochloric acid solution and hydrogen peroxide solution in the presence of an organic solvent. The process according to claim 1, characterized in that said solvent is n-hexane, dichloromethane or toluene. The process according to claim 1, characterized in that the aqueous hydrochloric acid solution and hydrogen peroxide solution are used in an amount of 6.0 to 8.0 equivalent weights, respectively, with respect to the disulfide compound of formula (XI). The process according to any one of claims 1 to 3, characterized in that the reaction temperature is 35 to 45°C.

Inventors: CHOI JONG KWON, CHUNG IN BAE, HEO TAE HO, LEE JAE CHOL, SA JONG SIN, SUH BYOUNG WOO, CHOI, JONG KWON, CHUNG, IN BAE, HEO, TAE HO, LEE, JAE CHOL, SA, JONG SIN, SUH, BYOUNG WOO
Applicants: LUCKY LTD, LUCKY LTD.
Application year: 1994
Main classification: C07D403
IPC codes: C07D521, C07D231, C07D401